Problem

(1 point) Rework problem 23 from section 2.4 of your text involving congressional committees. Assume that the committee consists of 11 Republicans and 6 Democrats. A subcommittee of 4 is randomly selected from all subcommittees of 4 which contain at least 1 Democrat.
What is the probability that the new subcommittee will contain at least 2 Democrats?

Answer

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Answer

So, the final answer is 53119.

Steps

Step 1 :Calculate the total number of ways to form a subcommittee of 4 from 11 Republicans and 6 Democrats. This is given by (174)=2380.

Step 2 :Calculate the number of ways to form a subcommittee of 4 with at least 2 Democrats. This can be broken down into two cases:

Step 3 :Case 1: The subcommittee has exactly 2 Democrats. There are (62) ways to choose the 2 Democrats and (112) ways to choose the 2 Republicans. So there are (62)×(112)=15×55=825 ways for this case.

Step 4 :Case 2: The subcommittee has more than 2 Democrats. This can be either 3 or 4 Democrats. For 3 Democrats, there are (63)×(111)=20×11=220 ways. For 4 Democrats, there are (64)=15 ways (since all 4 members of the subcommittee are Democrats).

Step 5 :Adding these up, there are 825+220+15=1060 ways to form a subcommittee of 4 with at least 2 Democrats.

Step 6 :The probability that the new subcommittee will contain at least 2 Democrats is therefore 10602380=53119.

Step 7 :So, the final answer is 53119.

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